Refrigeration system including accumulator means



Feb. 25, 1969 D. D. WILE ETAL REFRIGERATION SYSTEM INCLUDING ACCUMULATOR MEANS Filed Aug. 1, 1967 Sheet 'llzllllllllllnlltillllz; 1.9.

N mhm s m 06 M E CM Y V/A/ E 3 M 0 5 .0 L05. T E00 A 5 0% M uomm munzou I OF mwmzmozou REFRIGERATION SYSTEM INCLUDING ACCUMULATOR MEANS Sheet Filed Aug. 1, 1967 Qm v United States atent D 2 Claims ABSTRACT OF THE DISCLOSURE A refrigerant flow control apparatus for use with a defrosting system in which liquid refrigerant is returned to the compressor in a controlled manner to prevent damage to the compressor from slugs of condensed refrigerant. The principal improvement resides in a separate liquid refrigerant storage chamber which increases the capacity of the unit for retarding liquid refrigerant.

Background and summary of the invention This invention relates to refrigeration apparatus and more particularly to improvements in the manner of returning gaseous and liquid refrigerant to the compressor of such apparatus during a hot gas defrosting operation.

The apparatus of the invention is particularly useful in connection with refrigerating systems which employ hot gas defrosting. In such systems, portions of the hot gases passing through the evaporator or refrigerator coil are condensed to form slugs of liquid refrigerant, which, if permitted to pass into into the compressor, may result in damage to the compressor.

The type of system to which the present invention generally pertains is described in US. Patent 3,163,998, issued to Wile et al. on Jan. 5, 1965. One of the problems with operating a unit as described in the Wile et a1. patent is that if the level of liquid refrigerant rises too high in the separation chamber, it is carried along with the vapor and does not settle out to effect proper separation as intended. Thus, the capacity of the unit for retarding liquid refrigerant becomes considerably less than the total volume; and in actual practice, it has been found that the capacity may be limited to as little as /2 of the volume of the chamber.

In the improved apparatus of the present invention, the system employs t-wo chambersone for separating the liquid and gaseous refrigerant and one for storing the liquid refrigerant-thereby greatly increasing the capacity of the unit for retarding liquid refrigerant.

It is therefore a principal object of the invention to provide an improved defrosting system which will permit the return of gaseous refrigerant from the evaporator and a controlled return of liquid refrigerant with greater capacity for retarding the liquid refrigerant than has heretofore been available.

Another object of the invention is to provide improvements in adding refrigerant vapor to the stream of refrigerant returning to the compressor in a controlled amount by employing a first chamber for separating liquid and vaporous refrigerant and a second chamber for storing liquid refrigerant so as to increase the overall capacity of the unit.

Additional objects and advantages will be apparent 3,429,139 Patented Feb. 25, 1969 from the following detailed description taken with the accompanying drawings.

Brief description of the drawings FIGURE 1 is a schematic diagram of a refrigerating sys tem employing the apparatus of the present invention.

FIGURE 2 is a cross-sectional view of a preferred embodiment of the invention.

FIGURE 3 is a cross-sectional view taken along the plane of 33 of FIGURE 2.

Description In the preferred embodiment of the invention, FIG- URE 1 illustrates a refrigeration system in which the factors embodying the invention have been diagrammatically incorporated, and where hot gas from the compressor may be delivered directly to the coiling or conduits of the evaporator when desired to effect defrosting of the coil of surfaces of the evaporator. During this operation, the evaporator functions in a manner similar to the condenser in the normal refrigeration cycle so that the gaseous refrigerant used to effect the defrosting is condensed, or at least a portion thereof may be condensed, depending on the quantity of heat required to raise the temperature of the evaporator surface sufficiently to effect the defrosting operation. The condensed refrigerant, in accordance with the invention, is metered, or returned at a controlled rate to the compressor and at such a rate as may be handled by the compressor without damage thereto, avoiding the passing to the compressor of large quantities of refrigerant which would be detrimental thereto.

Referring now to FIGURE 1, during the refrigeration cycle, the compressor is designated by figure l0, and may be of any of the conventional forms. The compressor 10 compresses the gaseous refrigerant and forces it into the line 20. The refrigerant then passes into the condenser 12 and into receiver 14. From the receiver, the liquid refrigerant flows through line 24 and into the refrigerant flow retarding unit 34, exchanging heat therein, and then on into line 26 to expansion valve 16. From the expansion valve, the liquid refrigerant expands and passes into evaporator 18 whereupon it becomes evaporated and performs the cooling operation. From the evaporator the refrigerant passes into the evaporator outlet line 28, and into the refrigerant flow retarding unit 34. In the refrigerant flow retarding unit, the gaseous refrigerant and any liquid refrigerant which during normal refrigeration operation is present is retarded and heated and the gaseous refrigerant passes into the low pressure, or suction line 22; the refrigerant then passes into the compressor 10, and the cycle is repeated.

In accordance with the invention, when frost has accumulated on the surface of the evaporator, the hot gas from the compressor 10 may be by-passedto the evaporator 18 by means of control valve 32 which allows the hot gas refrigerant to pass through line 30 and into the evaporator 18, thus heating the evaporator and removing the frost therefrom. From the evaporator 18, the liquid and gaseous refrigerant passes through into the evaporator outlet line and into the flow retarding unit 34. Here the liquid is retained and then metered in controlled quantities, into suction line 22 by commingling with gaseous refrigerant which aspirates the liquid refrigerant. The liquid refrigerant, along with gaseous refrigerant, then flows back to compressor 10. When defrosting is complete, valve 32 is then closed, and the normal refrigerant cycle, as described above, continues. During this defrosting operation, the pressure rises in the evaporator line 15 and closes the expansion valve 16. This, in turn, blocks the flow of refrigerant flowing in lines 24 and 26 and through the heat exchanger.

Referring now to FIGURE 2, which is a cross-sectional view illustrating a preferred embodiment of the flow retarding unit 34, the separation tank 62 is connected to a refrigerant storage tank 70 by way of a pipe 72. Tank 62 is sealed at opposite ends by end caps 64 and 6S; and an inlet connection 66 is provided in end cap 64 through which refrigerant from evaporator 18 flows into the tank via line 28. The entering refrigerant flows into a discharge segment 38 which is surrounded by a finned coil heat exchanger 36 fed with liquid refrigerant from the receiver 14 through line 24. The other end of heat exchanger coil 36 returns refrigerant to expansion valve 16 through line 26. Thus, a means is provided for exchanging heat between the cold vapor refrigerant and the liquid refrigerant in the high pressure liquid line 24. The gas refrigerant leaves the discharge segment 38 and fiows into the heat exchanger chamber 40 which comprises an outer shell member 44, and an end member 42 which is proximate to the terminal portion of discharge segment 38. The refrigerant being discharged by this discharge segment 38 is then discharged over the heat excanger coils 36 and is retained by the end of the heat exchanger chamber 42 so that it is forced to flow over the heat exchanger coils and out of the opposite open end 46 of the chamber 40 and into the refrigerant separation chamber 48.

The refrigerant separation tank 62 communicates with the refrigerant storage tank 70 through a first tube 76 for the transfer of liquid by gravity from tank 62, and a second tube or pipe 72 which provides a fiow path for gas to one end of the storage tank. A refrigerant stor age chamber 49 in tank 70 is defined by an end cap 80 and a baflle t and a flow control chamber 54 is defined between baffle 50 and a second baffle member 55. Also provided in the refrigerant storage chamber 49 is a screen member 56 which protects a metering aperture or orifice 58, located in the lower portion of the first baffle member 50. The screen member 56 is provided for preventing the ingress of extraneous matter into the orifice 58 from the lowermost region of the refrigerant storage chamber 49. Thus, the aperature 58 in the baffle member 50 affords fluid communication between the refrigerant storage chamber 49 and the iiow control chamber 54.

The second bafile member 55, which terminates the flow control chamber 54 provides a discharge chamber 60 closed off by end cap 81. The second bafile member 55 is provided with an opening 59, which is formed by removing a lower segment of the baflle 55 (see FIGURE 3) providing a means for the refrigerant vapor and metered liquid refrigerant to enter into the discharge chamber 60 during the defrost cycle.

From this point in the discharge chamber 60, the vapor refrigerant is withdrawn from the refrigerant flow retarding unit 34 and into the compressor suction line 22. During the defrost cycle, the heat exchanger coils 36 become inoperative, and gaseous refrigerant is delivered directly to the evaporator 18, as previously discussed. From the evaporator, the condensed liquid and gaseous refrigerant passes into the discharge segment 38 of the flow retarding unit. From the discharge segment the liquid refrigerant passes through the heat exchanger chamber 4%) and into the separation chamber 48. There the gaseous refrigerant is separated from the liquid phase and flows down through tube 72 into the flow control chamber 54, while the liquid refrigerant flows down through the tube 76 into the refrigerant storage chamber. The upper portion of tube 76 may extend above the bottom of tank 62; and a vertical slot 84 is formed in the tube to allow the liquid to drain into the tube. The liquid refrigerant collects in storage chamber 49 and passes through the screen member 56, and through the aperture 58, the size of this aperture controlling the flow of liquid refrigerant into the flow control chamber 54. The combined gaseous and liquid refrigerant then flows through aperture 59 into the discharge chamber 60, and then into the suction or low pressure line 22. The liquid refrigerant is returned with the gaseous refrigerant to the compressor 10 at a controlled rate which the compressor can handle without damage thereto.

A restriction, such as orifice 90, may be provided in tube 72 to provide a resistance to flow of gaseous refrigerant through tube 72 and thus increase the pressure on the liquid refrigerant in chamber 80. The flow of liquid through orifice 58 will then be influenced by this added pressure in addition to the head of liquid in chamber above orifice 58.

It should also be pointed out that the particular flow control arrangement provided by baffies 50 and 55 need not be employed. For example, a metering or bleed tube could be provided between the storage chamber and a gas conduit connecting separation chamber 48 and the compressor directly.

While this invention has been described in connection with a certain specific embodiment thereof, it is to be understood that this is by way of illustration and not by way of limitation; and the scope of the appended claims should be construed as broadly as the prior art will permit.

What is claimed is:

1. In combination with a refrigeration system, including a compressor, a condenser, and an evaporator, means for defrosting said evaporator without shutting ofi the compressor, said means including: a liquid refrigerant flow retarding unit interposed in the suction line between the evaporator coil and the compressor for retarding liquids in the refrigerant flowing from the evaporator to the compressor during defrosting operations, said unit comprising a first tank providing a separation chamber into which refrigerant containing a considerable amount of vapor is introduced during defrosting operations from the evaporator; a second tank providing a refrigerant storage chamber; means defining a first flow path for liquid refrigerant from said separation chamber to said liquid storage chamber; means defining a second flow path for gaseous refrigerant from said separation chamber to said compressor; and means for metering the flow of liquid refrigerant from said storage chamber to said second flow path, whereby liquid refrigerant is returned to said compressor in a controlled manner.

2. In combination with a refrigeration system, including a compressor, a condenser, and an evaporator, means for defrosting said evaporator without shutting oif the compressor, said means including: a liquid refrigerant flow retarding unit interposed in the suction line between the evaporator coil and the compressor for retarding liquids in the refrigerant flowing from the evaporator to the compressor during defrosting operations, said unit comprising a first tank providing a separation chamber into which refrigerant containing a considerable amount of vapor is introduced during defrosting operations from the evaporator; a second tank providing a refrigerant storage chamber and a flow control chamber; means defining a first flow path for liquid refrigerant from said separation chamber to said liquid storage chamber; means defining a second flow path for gaseous refrigerant from said separation chamber into said flow control chamber, a baffle dividing said refrigerant storage chamber from said flow control chamber, means defining a metering orifice in said bafile to permit the controlled flow of liquid refrigerant from said storage chamber to said flow control chamber, a second baffle in said second tank dividing said flow control chamber from a discharge chamber, and conduit means extending from said dis- 5 6 charge chamber to said compressor for return of vapor 3,012,414 12/1961 La Porte 62-278 XR containing refrigerant to said compressor. 3,021,693 2/ 1962 Anne 62-278 References Cited MEYER PERLIN, Primary Examiner.

UNITED STATES PATENTS 5 us. 01. X.R. 2,953,906 9/1960 Quick 62-278 

